Insulating-isolating barrier system for electrical distribution equipment buswork

ABSTRACT

A barrier system includes elongated, insulative, high impact resistant isolating barrier members clamped in semi-embracing relation with the horizontal bus runs in an electrical switchboard and the like. These horizontal bus runs are interrupted by bus joints electrically connecting them with riser bus; these joints being isolated by an enclosure comprising an insulative collar and a removable, insulative cover. The barrier members, joint enclosures, and insulative barrier panels and support bases isolating the riser bus all cooperate to afford an essentially impenetrable barrier protecting the buswork and preventing inadvertent human contact therewith.

BACKGROUND OF THE INVENTION

The present invention relates to electrical distribution equipment andparticularly to an insulating-isolating barrier system for the busworkthereof.

In the interests of safety, it is most desirable to isolate the busbarsof switchboards, switchgear, and the like from inadvertent contact,either by humans or foreign objects. Obviously human contact with theselive parts can result in fatal electrocution. Of equally hazardousconsequences are those situations where a foreign metal object, such asa wrench, is inadvertently dropped onto live bus or left in contact withthe bus when voltage is applied. Such happenstances can and often docreate a phase-to-phase fault accompanied by explosive arcing injuriousto personnel standing by.

It is accordingly an object of the present invention to provide aninsulating-isolating barrier system for the live parts of electricaldistribution equipment.

A further object is to provide a barrier system of the above characterwherein components thereof may be readily removed for inspection andmaintenance.

Another object is to provide a barrier system of the above characterwhich is effectively impenetrable from without and yet accommodateseffective convection cooling of certain current carrying parts.

An additional object is to provide a barrier system of the abovecharacter wherein the components thereof are readily fabricated andconvenient to assemble.

Other objects will in part be obvious and in part appear hereinafter.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a barriersystem for insulating-isolating live parts of electrical distributionequipment in the form of switchboards, switchgear, and the like.Included in this system is a vertical array of modular insulative basesassembled to the equipment frame and providing a plurality ofside-by-side channels in which riser busbars are individuallyaccommodated and supported. These bases also serve as rear barrier wallsfor cubicles accommodating electrical devices fed from the riser bus.

Insulative barrier panels, secured to the bases, close off thesechannels to isolate the riser bus therein. Apertures in these panelsaccess the individual riser busbars for bus joint electrical connectionwith respective busbars of plural horizontal bus runs. To isolate thesebus joints there is provided insulative enclosures, each consisting of acollar and a mating cover. Cooperating with these joint enclosures areelongated, high impact resistant, insulative barrier members clamped insemi-embracing relation with the horizontal bus runs extending betweenbus joints to thus provide an essentially impenetrable barrier for theequipment buswork effective in precluding inadvertent contact with theselive, current carrying parts by humans and foreign objects.

The invention accordingly comprises the features of construction andarrangement of parts which will be exemplified in the constructionhereinafter set forth, and the scope of the invention will be indicatedin the claims.

For a better understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconjunction with the accompanying drawings in which:

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an electrical switchgear including apair of side-by-side vertical sections;

FIG. 2 is a perspective view looking into one of the cubicles of theswitchgear of FIG. 1;

FIG. 3 is a front view of a modular insulative support base utilized inthe switchgear of FIG. 1;

FIG. 4 is an end view of the support base of FIG. 3;

FIG. 5 is a sectional view taken along line 5--5 of FIG. 3;

FIG. 6 is a sectional view taken along line 6--6 of FIG. 3;

FIG. 7 is a sectional view taken along line 7--7 of FIG. 3;

FIG. 8 is a vertical sectional view taken along the centerline of one ofthe riser busbar channels provided in the rear face of the base of FIG.3;

FIG. 9 is a fragmentary perspective view of the runback supportingportion of the base of FIG. 3;

FIG. 10 is a perspective view of one of the runbacks utilized in theswitchgear of FIG. 1;

FIG. 11 is a perspective view, partially broken away, of a copper riserbusbar utilizable in the switchgear of FIG. 1;

FIG. 12 is a perspective view, partially broken away, of an extrudedaluminum riser busbar utilizable in the switchgear of FIG. 1;

FIG. 13 is a plan view of an electrical joint between a horizontalbusbar and the riser busbar of FIG. 11;

FIG. 14 is a perspective view of the power connector utilized in the busjoint of FIG. 13;

FIG. 15 is a simplified elevational view illustrating the horizontal busruns interconnecting adjacent switchgear vertical sections;

FIG. 16 is an exploded perspective view of an isolating enclosure forthe bus joint of FIG. 13;

FIG. 17 is an exploded, fragmentary perspective view illustrating theassembly of isolating barriers to the horizontal bus runs of FIG. 15;

FIG. 18 is a plan view, partially broken away, of the bus joint of FIG.13 as adapted with the isolating enclosure of FIG. 16 and a horizontalbus run as adapted with the isolating barriers of FIG. 17;

FIG. 19 is an elevational view of the isolated bus joint and horizontalbus run of FIG. 18;

FIG. 20 is a sectional view taken along line 20--20 of FIG. 19; and

FIG. 21 is a sectional view taken along line 21--21 of FIG. 19.

Corresponding reference numerals refer to like parts throughout theseveral views of the drawings.

DETAILED DESCRIPTION

The present invention is embodied in an electrical switchgear generallyindicated at 20 in FIG. 1 and comprising one or more vertical sections20a. Each vertical section includes a cubical steel framework consistingof width posts 22, depth posts 24 and vertical posts 26 rigidly joinedat the frame corners in mutually perpendicular relation. Secured tothese posts are suitable panels, such as side panel 27 seen in FIG. 1,to provide a cubical enclosure, as well as partitions to createindividual compartments or cubicles accessed by doors 28 hinged to thevertical posts. Within each cubicle is an electrical device, such as acircuit breaker 30 whose operating handle 30a protrudes through acentral opening 28a in the cubicle door. Looking into a representativecubicle of one of the switchgear vertical sections, as seen in FIG. 2,the rear wall thereof is provided by a modular support base, generallyindicated at 32, of a structurally rigid, electrically insulativematerial, such as glass fiber polyester, formed, for example, by amolding process. These bases are mounted in end-to-end vertical relationto vertical stringers 34 by self-tapping screws 35 utilizing verticalpatterns of holes 35a preformed in the lateral edge portions of thebases (FIG. 5); the stringers being affixed to the switchgear sectionframework at an appropriate depth. As seen in both FIGS. 2 and 3, thefront face of each base is formed to provide three rectangular,vertically elongated, relatively deep depressions 36, in side-by-siderelation for accommodating L-shaped, run-in line straps 38 (FIG. 2)which are respectively electrically connected with separate vertical orriser busbars and, together with these riser busbars, are physicallymounted to the base, as will be described in connection with FIG. 8.Also formed in the front side of base 32 in vertical alignment belowdepressions 36 are side-by-side depressions 42 in which are mountedload-side runbacks 44, as will be detailed in conjunction with FIGS. 8through 10. The line straps 38 are electrically joined with andphysically support separate male stabs 39 using bolts 39a, while therunbacks 44 physically mount and are electrically joined by bolts 45awith separate male stabs 45. These stationary male stabs are disposed tomate with line terminal disconnects 30b and load terminal disconnects30c of a drawout circuit breaker 30, as seen in FIG. 8; racking movementof the breaker being supported by side rails 30d seen in FIG. 2.

Still referring to FIGS. 2 and 3, interphase isolation is provided bythe base in the form of a pair of barrier walls 46 separatingdepressions 36 and 42, while phase to frame isolation is afforded byoutboard barrier walls 48. A pair of rectangular wells 50 locatedbetween each vertically spaced pair of depressions 36 and 42 serve torecess the heads of bolts 49 securing the riser busbars to the base 32,as also will be seen in connection with FIGS. 5 and 8. The bolt heads,being live, are isolated by caps, one seen at 51 in FIG. 3, which arepress-fitted in the countersunk portions of the bolt holes 50a preformedin the base. Rectangular recesses 52 in the front surface of the baseconstitute coring, while appropriately located, preformed holes 53 maybe utilized to mount current transformers (not shown) in embracingrelation with either the line straps 38 or the runbacks 44 of eachphase. The horizontal pattern of preformed holes 54 may be utilized tosecure a transverse brace (not shown) to each base should additionalbracing be needed to withstand the extreme electrodynamic forcesassociated with extraordinarily high levels of shortcircuit faultcurrent.

As will be described, bases 32, once mounted to the switchgear frame inend-to-end vertical relation, serve to support in parallel,side-by-side, isolated relation typically three vertical or riserbusbars, which are seen in FIGS. 11 and 12 to be of H-shapedcross-section. The riser busbar 56 of FIG. 11 is formed of copper withits H-shaped cross-section created by assembling a pair of copperrectangular cross-sectioned bars or flanges 56a to a series ofinterconnecting U-shaped copper webs 56b utilizing bolts 56c. FIG. 12depicts an alternative, aluminum busbar 58 extruded in H-shapedcross-section with flanges 58a interconnected by an integral web 58b. Aswill be seen, a series of holes 56d preformed in the separate webs 56bof each copper riser busbar or the preformed holes 58c in the web ofeach aluminum busbar are utilized in affixing the riser busbars to thebases 32 and to accommodate bolted joints with line straps 38 (FIGS. 2and 3). The separations 56e between the copper busbar webs 56b and theopenings 58d created in the aluminum busbar web 58b are so located as toaccommodate the rearward extension of runbacks 44, as will be described.

Referring to FIGS. 4 and 5, the back side of each base 32 is integrallyformed with four outstanding, vertically extending walls 60 arranged inequally spaced, parallel relation such to define three channels 62coextensive with the length of each base. When the bases are assembledin vertical, end-to-end relation to stringers 34 (FIG. 2), thesechannels are continuous for the full height of the switchgear verticalsection. In this connection, as seen in FIG. 3, the lower edge of eachbase is provided with tongues 63a which interfit with grooves 64acreated in the upper edge of each base incident to their end-to-endassembly. Also as seen in FIGS. 3 and 8, a transverse wall 64outstanding from the front side of each base at its upper edge and atransverse wall 63 outstanding from its lower edge cooperate withpartitions 65, seen in FIGS. 2 and 8, in fully separating verticallyadjacent cubicles.

Returning to FIG. 5, the floor 62a of each channel 62 is formed with apair of deep, parallel running troughs 62b which receive the forwardlyextending portions of the copper busbar flanges 56a or the aluminumbusbar flanges 58a depending on which of the H-shaped riser busbars 56or 58 are laid in the channels. While FIG. 5 shows a copper riser busbar56 laid in the left channel 62 and an aluminum riser busbar 58 in thecenter channel, it will be appreciated that for a particularinstallation the riser bus will either be all copper or all aluminum.The width of the troughs 62b is illustrated as being greater than theflange thickness to show that flanges of increased thickness and greaterampacity can be accommodated. The depth of the troughs 62b is such thatthe forward edges of the riser bus flanges are spaced from the groovebottoms while the busbar webs rest on the channel floors 62a, asillustrated in FIG. 5. Centrally located in the wells 50 noted in FIGS.2 and 3 are the preformed through-holes 50a, countersunk from bothsides, for accommodating the bolts 49 inserted from the front side ofthe base (see also FIG. 8). Nuts 49a are then threaded down on the boltshanks 49b so as to clamp the bolts to the base with their shanksprojecting out beyond the floors 62a of their respective channels 62.Thus, when the riser busbars are laid in the channels the bolt shanks49b project through the preformed holes in the busbar webs. Second nuts49c are then torqued down on these bolt shanks to securely clamp theriser busbars, either the copper busbars 56 as seen in FIG. 5 of thealuminum busbars 58, to the bases 32.

In addition to bolts 49, a pair of spline bolts 66 are utilized tofurther secure each riser bus to the bases 32 and also to support andelectrically connect an L-shaped line strap 38 to each riser busbar,which in FIG. 8 is seen to be a copper busbar 56. Thus, one of each pairof spline bolts 66 has its intermediate spline portion 66a swaged into apreformed hole 67 located in the lower portion of each line strapdepression 36 formed in the front side of base 32. The other one of eachspline bolt pair has its spline portion 66a swaged into a countersunkhole 68a formed in a rectangular copper spacer 68 which is accommodatedin a close-fitting opening 36a in the channel floor 62a otherwiseseparating each front side line strap depression 36 from its associatedriser bus channel 62. The upper and lower edges of opening 36a areforwardly offset to create lips 36b (see also FIG. 6) which cooperatewith upper and lower spacer projections 68b to seat spacer 68 with itsrear surface flush with the channel floor 62a and its front surfaceflush with the bottom surface 36c of line strap depression 36. Theforwardly extending threaded shanks 66b of spline bolts 66 are insertedthrough holes 38a in line strap 38 and nuts 66c are applied to clamp theline strap to the base and to effect a bolted electrical joint withspacer 68. The rearwardly extending threaded shanks of the spline boltsproject through the copper riser bus web holes 56d to receive nuts 66dfurther clamping the riser bus to the base and effecting a boltedelectrical joint with spacer 68.

When aluminum riser busbars 58 are utilized, their electrical jointswith the line straps or run-ins may be of a bolted-welded configurationsuch as disclosed in commonly assigned, U.S. Pat. No. 4,288,656.

To isolate the rearward extensions of runbacks 44 from the riserbusbars, the base is integrally formed with a rearwardly extending,rectangular sleeve 70 outstanding from the floor 62a of each channel 62,as seen in FIGS. 7, 8 and 9. Riser bus clearance for these sleeves isafforded by the gaps 56e in the copper busbar webs 56b (FIG. 11) or theopenings 58d in the aluminum busbar webs 58b (FIG. 12). An integral,vertically oriented partition 70a divides the sleeve interior into tworectangular passageways 70b, as best seen in FIGS. 7 and 9, which openinto associated depression 42 in the front side of base 32. As seen inFIG. 10, each runback is constituted by a pair of copper bars 44a whoseforward terminations are clamped by bolts 45a in electrical connectionwith an intervening tongue 45b integrally formed with male stab 45. Atan appropriate intermediate point, a pair of brackets 72 are clampedtogether between the runback bars by bolts 72a to thus create a runbackassembly with bars 44a secured in closely spaced, parallel relation.Each bracket is equipped with a pair of laterally turned, apertured ears72b which rest on four pedestals 42a outstanding from the floor of eachdepression 42, as best seen in FIG. 3, when the runback assemblies areinserted through sleeves 70 from the front side of the base. As seen inFIG. 8, self-tapping screws 42c are driven into blind holes 42b formedin these pedestals to clamp ears 72b thereto and, in turn, secure therunback assemblies to base 32.

The utilization of a pair of bars in each runback 44 is seen to promotemore secure support of the runbacks by the base; the sleeve partitions70a being a significant factor in this regard. Moreover, greaterconductor surface area is created to afford increased current carryingcapacity without having to enlarge the vertical dimension of the runbackconductors. As seen in FIG. 10, the rearward terminations of the runbackbars 44a are apertured for bolted electrical connection with cable busconnectors (not shown), which, incidentally, further serve to secure thebars in parallel, closely spaced relation.

In FIGS. 13 and 14 there is illustrated a power connector 80 which isutilized to make the electrical connections or bus joints between thecopper riser busbars 56 of FIG. 11 and horizontal busbars 82 which inFIG. 15 are seen to run between corresponding riser busbars of adjacentswitchgear vertical sections 20a (FIG. 1) and to a power source (notshown) feeding the switchgear sections in parallel. The connectors aregenerally U-shaped having legs 80a appropriately relieved, as indicatedat 80b, to seat on the rearward edges of the riser bus flanges 56a. Weldfillets 81 are then laid down to join the connector legs with the riserbus flanges pursuant to creating a welded electrical joint between thepower connector and the riser busbar. The planar rearwardly facingsurface 80c of the power connector is provided with tapped bores 80daccommodating bolts 83 for effecting a bolted electrical joint betweenthe power connector and a horizontal busbar 82. In the case of thealuminum riser busbars, electrical joints with the horizontal busbarsmay be effected in the manner disclosed in commonly assigned, U.S. Pat.No. 4,298,771 the disclosure of which is specifically incorporatedherein by reference.

To isolate the riser-horizontal bus joints from contact by humans andforeign objects, an insulative enclosure therefor, seen in FIGS. 16, 18and 19, is provided. This enclosure is constituted by a moldedrectangular collar 86, a molded cover 88, and, in those situations wherea horizontal bus run terminates at a particular power connector, an endpanel 90. To protect and isolate the horizontal bus runs between powerconnectors, a pair of elongated, insulative barriers 92, best seen inFIG. 17, are assembled in partially enclosing relation thereto. Finally,to isolate the riser busbars, a barrier sheet 94, seen in FIG. 15, issecured to the back side of each base 32 to close off the riser buschannels 62. Rectangular openings 94a (FIG. 18) in the barrier sheetprovide clearance for the power connectors 80 so that the welded jointsbetween the power connectors and the riser busbars may be made beforethe barrier sheet is secured to the base.

Before the joint between the power connectors and the horizontal busbars82 are made, collars 86 of the bus joint enclosures are slipped over thepower connectors. Once the bus joints are made, covers 88 are applied.From FIGS. 16 and 18, it is seen that the upper and lower skirts 88a ofthe cover underlap the upper and lower sidewalls of the collar to fullyisolate the bus joint from above and below. The length of these skirtsis made sufficient to isolate bus joints involving double-bar horizontalbus runs, as seen in FIG. 18. A conductive spacer 95 is incorporated inthe bus joint to maintain the horizontal busbars in closely spaced,parallel relation for high ampacity, cool running performance. The faceof the cover is formed having a rectangular cavity 88b to affordclearance for the heads of the joint bolts 83. Also molded into thecover face is a rectangular, horizontally elongated, hollow extension88c which serves to accommodate the projection flange of the aluminumpower connector utilized in the bolted-welded aluminum bus joint of theabove-noted U.S. Pat. No. 4,298,771. Extension 88c also serves as aconvenient handle for safely removing the cover for in-service jointinspection. To accommodate those situations where the horizontal bus runterminates at a bus joint, collar 86 is molded with opposed, laterallyextending ears 86a, while the cover is molded with opposed, laterallyextending tangs 88d having a slot 88e therein. Panel 90 is equipped witha projection 90a, which is inserted in this tang slot, and an L-shapedbracket 90b, which is apertured to receive a screw 91 (FIG. 18) threadedinto a bore 91a provided in collar ears 86a. The panel 90, thusassembled to the bus joint enclosure, effectively closes off theotherwise open side of the enclosure beyond the horizontal bus runtermination to isolate the bus joint from inadvertant human contact.

Turning to FIG. 17, except for their terminations, the surfaces of theindividual horizontal busbars 82 are coated with a layer 82a of primaryinsulation which also covers the surfaces of holes 82b punched therein.As seen in FIG. 20, these holes provide clearance for a series of screws96 serving to clamp barriers 92 against the front and back sides of thehorizontal busbars throughout their runs between bus joints. As seen inFIG. 18, the upper and lower skirts 92a of these barriers do not closeoff the gap between the horizontal busbars so as not to obstructconvection cooling thereof. The primary purpose of these barriers is toprotect the busbar primary insulation 82a from impact damage, and thusare preferably formed of high impact resistant plastic material.

The barriers are molded with a co-extensive track 92b configured toslidingly receive an insulative strip 97 effective in concealing screws96 when positioned with its access holes 97a in non-registry with thescrew heads, as seen in FIG. 19.

To interconnect the horizontal bus run barriers with the bus jointenclosure, barrier track 92b is formed with opposed undercuts 92c (FIGS.17 and 21) serving to slidingly mount a clip 98, also seen in FIGS. 18and 19. With joint enclosure cover 88 in place, its tangs 88d arereceived in the recessed portion of tracks 92b on barriers 92 to eachside of the bus joint. The clips are then slid toward the bus joint tocapture the tangs and hold cover 88 in place. To preserve the captivepositions of the clips, they are dimpled, as indicated at 98a in FIG.21, for detenting engagement with holes 98b molded into the tangs.

It will thus be seen that the objects set forth above, among those madeapparent in the preceding description, are efficiently attained and,since certain changes may be made in the above construction withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

Having described our invention, what we claim as new and desire tosecure by Letters Patent is:
 1. An insulating-isolating barrier systemfor electrical switchboards and the like, said system comprising, incombination:a plurality of modular, insulative bases assembled inend-to-end vertical relation to a switchboard frame, said basesincluding a plurality of side-by-side channels in which switchboardriser busbars are individually supported; an insulative barrier panelsecured to each said base to close off said channels and isolate saidriser busbars therein, at least one of said panels having aperturestherein individually accessing said riser busbars for electricalconnection with separate power connectors, said power connectors makingbus joints between separate runs of horizontal busbars and said riserbusbars; separate pairs of elongated, insulative barrier members clampedin semi-embracing relation with said horizontal busbar runs extendingbetween said bus joints; and a joint enclosure for each said bus joint,said enclosure includingan insulative collar embracing said powerconnector; and a removable, insulative cover mating with said collar toenvelop said bus joint thereat, each said bus joint enclosure coverincludes a frontal wall and integral therewith separate upper and lowersubstantially rectangular skirts disposed in lapped relation with saidcollar.
 2. The barrier system defined in claim 1, wherein each said busjoint enclosure further includes a separate, insulative side panelattached to said collar and cover to close off a side of said enclosureotherwise left open by the absence of said barrier member pair due tothe termination of a horizontal bus run at the bus joint thereat.
 3. Thebarrier system defined in claim 1, which further includes meansselectively coupling each bus joint enclosure with the barrier memberpairs associated with the horizontal bus runs entering and leaving thebus joint thereat.
 4. The barrier system defined in claim 3, whereineach said bus joint enclosure cover includes opposed horizontallyextending tangs and at least the outer one of said pair of barriermembers includes a coextensive molded track, said coupling meanscomprising a clip slidingly mounted on said tracks of said outer barriermembers to each side of said cover, said clips being shiftable intoengaging relation with said cover tangs.
 5. The barrier system definedin claim 4, wherein said outer barrier member molded tracks additionallyslidingly receive insulative strips for concealing the heads of screwsclamping said barrier member pairs to said horizontal bus runs.